This invention relates to flexible elongated probes, such as borescopes or endoscopes, and is more particularly directed to a system and technique for propelling an elongated flexible insertion tube within narrow, tortuous passageways.
Long industrial borescopes are extremely useful in inspecting the condition of otherwise inaccessible passages, such as boiler tubes in a steam generator or hydraulic lines in a turbine or jet engine. However, these same passageways tend to be somewhat tortuous. Consequently, because of twists and turns in the passageway, and because of friction between the sides of the insertion tube and the walls of the passageway, the distance into the passageway that the borescope insertion tube can be pushed or pulled is quite limited.
Ideally, means should be provided on the insertion tube to permit it to advance itself through passages such as curved pipes. Such means would need the following features:
axial thrust distributed along the insertion tube to avoid buckling, stretching, or excessive insertion tube-wall friction; PA1 reversibility of movement to permit insertion or withdrawal of the insertion tube in the same manner; PA1 controllability from the proximal end of the insertion tube; PA1 simplicity, reliability, and low expense; PA1 small or negligible increase in insertion tube diameter; PA1 possibility of operation when only a part of the insertion tube is inserted into the device to be inspected; i.e., no need to install the device on the tube as the tube is being inserted; PA1 applicability to existing insertion tubes, either permanently or as a removable option; and PA1 insensitivity to the diameter of the pipe or passageway in which the borescope insertion tube in utilized.
However, present-day insertion tubes are inserted or withdrawn only by applying force at the proximal end, distal end, or both. No one has proposed a technique which will provide the foregoing advantageous features.